This invention relates to apparatus for dispensing units of currency. The invention will be described in the context of a coin dispenser, but the techniques could also be applied to the dispensing of banknotes.
Various types of devices are known for dispensing coins, for example in change-giving apparatus. Coins are commonly stored in tubes within each of which coins of a respective denomination are stacked face-to-face. The coins are usually dispensed by sliding the bottom-most coin laterally out of the stack.
It is also known to provide an actuator, in the form of a motor, which can be used to dispense coins selectively from two separate stores, using clutch arrangements. See for example WO 94/16411.
It would be desirable to provide an improved arrangement for dispensing coins, incorporating an inexpensive, low-power and compact drive mechanism.
Aspects of the present invention are set out in the accompanying claims.
In one aspect of the present invention, a clutch for selectively causing a dispensing operation to be performed in response to movement produced by an actuator comprises an electromagnet which can move a coupling member between a disengaged state and an engaged state. Preferably, the coupling member is moved towards the engaged state by the electromagnet, and is moved back to the disengaged state under the influence of gravity and/or by reversing the direction in which the clutch is driven (although if desired the various influences could have the opposite effects).
Preferably, the clutch has a driving member and a driven member which can adopt different relative positions, the coupling member in its engaged state limiting relative movement between the driving and driven members so that the driving member drives the driven member. It is envisaged that that driving and driven members would be arranged to rotate, preferably around a common axis, as this leads to a particularly compact arrangement. However, other arrangements are possible, such as having one or both of the members arranged for linear reciprocation.
The arrangement is preferably such that the coupling member is prevented from moving into its disengaged state in one relative position and/or its engaged state in another relative position. This would mean that the electromagnet would need to be operated only for a fairly brief time to cause clutch engagement (or possibly disengagement), therefore lowering the overall power consumption.
Preferably, with the coupling member in its engaged state, the driving member and driven member move relative to each other over a limited range, the coupling member transmitting the driving force to the driven member at one limit of the range and the coupling member being capable of shifting to its disengaged state of the other limit of the range. In between these limits, the coupling member is retained in its engaged state but is confined in the direction between the two states by an amount which progressively increases as the driving limit position is reached. This can be achieved by providing a ramp on one or both of the driving and driven members. Such an arrangement can have several advantages: (a) the coupling member can more readily enter its engaged state, (b) the relative freedom of movement of the coupling member means that interference between the driving and driven members can be avoided until the driving limit position is closely approached, without requiring precise tolerances in the dimensions of the clutch elements, and (c) the coupling member will more readily shift to its disengaged state when this is required.
Preferably, the coupling member is capable of rolling motion (for example it may be a roller or preferably a sphere) to assist in moving between its engaged and disengaged states and to reduce the chances of the coupling member sticking.
A clutch in accordance with the present invention can be made inexpensively and can be compact. Preferably, a single actuator, such as a motor, is used to drive a plurality of clutches each associated with a respective coin store. Preferably, there are three or more such clutches and coin stores. This means that fewer actuators are required than in many prior art arrangements, thus resulting in a less expensive and more compact arrangement, and also permitting the use of a larger and thus more powerful actuator. Depending upon the power of the chosen actuator, the arrangement may be such that the actuator can simultaneously dispense from a plurality of stores.